Question

the area of a circle is 78.5 square cm, and a subtending arc on a circle has an arc length of 6 pi. the estimated value of pi is 3.14. the measure of the angle sub tended by the arc is what?

Answer 1

we know that

area of a circle=pi*r²---------> r=√[area/pi
area=78.5 cm²
r=√[78.5/pi]-------> r=√25------> r=5 cm

circumference=2*pi*r------> 2*pi*5----> 10*pi cm

if 360° (full circle) has a length of-----------> 10*pi cm
 X------------------------------> 6*pi cm
x=6*pi*360/(10*pi)------> x=216°

the answer is 
216°